The present invention relates to a light beam deflection apparatus which incorporates a polygon mirror and is employed for, e.g., a laser printer, a bar-code reader, a laser copier, etc.
In the conventional light beam deflection apparatus, the polygon mirror rotates at a high rate, by means of a rotating disk linked to the polygon mirror. The rotating disk includes permanent magnets arranged on it and is driven by driving coils fixed on a base plate. The rotational torque of the polygon mirror is generated by the magnetic forces between the permanent magnets and the driving coils.
In the abovementioned apparatus, however, since the rotating disk, on which the permanent magnets and the polygon mirror are mounted, is joined to a rotatable axis, the reference surface on which the polygon mirror is attached is liable to be distorted when the permanent magnets are mounted on the rotating disk. Owing to this shortcoming, the distortion and/or an inclination of the polygon mirror surface has been relatively high.
To prevent the distortion of the polygon mirror, it is required to employ an adhesive which causes little distortion of the polygon mirror when the permanent magnets are adhered onto the rotating disk. Generally speaking, however, an adhesive causing little distortion is liable to be lower in the reliability of its adhesion, due to the weakness of its adhesive force.